> >> Would you please have a look at Simon's patch, in particular verify > >> whether it solves the performance dip in your testing environment? > >> https://www.postgresql.org/message-id/CANP8%2BjJuyExr1HnTAdZraWsWkfc-octhug7YPtzPtJcYbyi4pA%40mail.gmail.com > >> (Note there's an updated patch a few emails down the thread.) > >> > >> If it seems to fix the problem for you, I think we should mark yours > >> rejected and just apply Simon’s. > > Ok, I’ll try this patch with my use case. Basically, it’s not so easy > now since I’ve partitioned that big table to not have such problems > but there is a way to reproduce it once again. If it helps, I agree > that my should be rejected in favor of the Simon’s patch because my > patch just reduces replication lag but Simon’s seems to remove lag at > all.
I would agree except for the observation on toast indexes. I think that's an important enough use case that perhaps we should have both.
The exclusion of toast indexes is something we can remove also, I have recently discovered. When we access toast data we ignore MVCC, but we still have the toast pointer and chunkid to use for rechecking our scan results. So a later patch will add some rechecks.
So I don't think it is worth applying this patch now. I should add that I also had a patch that did this, posted earlier IIRC. That is not the reason to reject this, just me pointing out that I'm effectively rejecting my own earlier patch also.
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Simon Riggs http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
